A feeding system supplies a power inputted from an external source to another device through its output terminal, and may be for example a phase shifter used in an antenna shown in following FIG. 1.
FIG. 1 is a view illustrating a common antenna.
As shown in FIG. 1, the antenna includes a reflector 100, phase shifters formed on one side of the reflector 100 and radiators 104 on the other side of the reflector 100.
The phase shifter 102 changes phase of a power (rf signal) supplied to the radiators 104, thereby adjusting angle of a beam outputted from the radiators 104, i.e. tilting angle.
Since three phase shifters 104 are generally connected to one phase shifter 102, five phase shifters 102 have been required for feeding a power to fifteen radiators 104, i.e. realizing fifteen ports. Accordingly, five phase shifters 102 should be disposed in series on the reflector 100, and thus size of the antenna increases.
The phase shifters 102 are individually controlled, and thus it is difficult and inconvenient to achieve desired tilting angle of the antenna.